The present invention pertains to a safety belt warning system for use in vehicles.
Present Federal Regulations have now eliminated the more stringent requirements relative to vehicle safety belt systems which were mandated by earlier Federal Regulations. The present regulations require that both visible and audible alarms be provided and that the alarms be given for a limited time period subsequent to operation of the vehicle ignition switch. Further, if the driver fastens his safety belt prior to the expiration of the time period, the audible alarm is to terminate.
Thermal bimetal timers have been proposed for complying with the present Federal Regulations. However, it has been found that such devices may be unable to successfully achieve the desired result. More particularly, the present Federal Regulations also impose a predetermined tolerance on the time period which the bimetal type timer devices may be incapable of consistently achieving on a production basis and in the temperature range to which automobiles are exposed when in use.
The present invention is directed toward a novel electronic control circuit for safety belt systems which can consistently on a mass production basis achieve compliance with present Federal Regulations using conventional electrical circuit components in the typical environments to which these devices are subjected when in use in an automobile. Moreover, the invention can provide precise control of the time period without requiring greatly complicated and expensive circuit constructions. Further, the invention is adaptable to a number of different modes of application which provide further utility in systems where different requirements may be imposed.